Liver is a central organ of metabolism, and has a variety of important functions, such as biligenesis, excretion, detoxication, and the like. On the other hand, liver is said to be a silent organ due to its great reserve, and hardly develops symptoms, such as malaise, jaundice, edema, and ascites, so that its dysfunction tends to be perceived too late. It is generally known that an abundance of GOT (glutamic-oxaloacetic transaminase) and GPT (glutamic-pyruvic transaminase) are present in liver, and the blood GOT and GPT levels sensitively reflect the degree of hepatocellular necrosis, so that these levels are often used as convenient means for evaluating hepatic dysfunction.
Recent westernization of dietary habit, nutritional unbalance, and ingestion of alcohol or drugs have imposed increasing burden on liver, resulting in substantial increase in the number of patients suffering from fatty liver. Chronic liver diseases progress through repeated hepatocellular destruction and regeneration over years to cause hepatic fibrosis, and lead to cirrhosis or hepatocellular carcinoma. Patients suffering from such disease are also increasing.
There is no effective drug for liver diseases at present, and diet therapy and rest are the prevailing therapy. Though, for example, glycyrrhizin formulation, such as Stronger Neo-Minophagen C (registered trade mark, manufactured by MINOPHAGEN PHARMACEUTICAL, CO., LTD.) is sometimes used for chronic liver diseases, such glycyrrhizin formulation is inactivated in the intestines, so that desired effect cannot be expected through oral administration, and parenteral injection is the main route of administration. Thus patients suffer from regular injections, and even side effects, such as hypertension or hypokalemia, are reported to be produced.
On the other hand, various amino acid formulations are sometimes used for the purpose of ameliorating hepatic encephalopathy or hypoalbuminemia associated with liver diseases such as cirrhosis or hepatic insufficiency. However, such amino acid formulations are used with mere expectation of improvement in nutritional deficiency caused by liver diseases, i.e., improvement in nitrogen metabolism or reduction of blood ammonia level by balancing the plasma amino acid, rather than treatment of liver diseases.
There has recently been proposed an agent for improving liver function containing lactoperoxidase and/or lactoferrin as an active component (see Patent Publication 1). Lactoferrin is known to be contained in milks of various mammals.
However, lactoferrin is prone to thermal denaturation, and known to be denatured easily in ordinary high temperature pasteurization or the like process (see, for example, Non-patent Publications 1 to 3). Thus isolation or use of lactoferrin in industrial scale is restricted, and problems remain in cost and versatility.
Whey has recently come to be known to contain various components having physiological functions, such as components for protecting gastric mucosa (α-lactalbumin) However, no improving effect on liver function has been reported of milk or whey that has undergone ordinary pasteurization.
Patent Publication 1: JP-2001-226289-A
Non-patent Publication 1: Shokuhin Shinsozai Yuukou Riyou Gijutsu Series “Lactoferrin” (March 2000, Shadan Houjin Kashi Sougou Gijutsu Center)
Non-patent Publication 2: Nyugyo Gijutsu, Vol. 51, 2001, “Miruku no Rakutoferin (Lactoferrin in Milk)”
Non-patent Publication 3: Journal of Dairy Science Vol. 74, No. 1, p 65-71, 1991